Guided Munitions Protected by an Aerodynamic Cap

ABSTRACT

In the field of steered munitions intended to destroy a target after at least one flight phase followed by a target approach phase, a munition comprises a munition body of cylindrical shape of longitudinal axis having, on the same side as a front end of the munition which is the end intended to be directed toward the target, a front body comprising an optic of a guidance device that guides said munition toward the target, a cap for protecting the optic, secured to the munition body, characterized in that the protective cap comprises at least one recess having a pyrotechnic device intended to destroy said protective cap so as to free the optic and make the munition guidance device operational during the target approach phase. Application: steered or guided munitions such as those of the rocket or projectile type, or missiles.

The invention relates to guided munitions comprising a protective capthat protects a guidance device guiding the munition toward a targetthat is to be destroyed.

Guided or steered munitions, such as those of the rocket or projectiletype or missiles are equipped with guidance electronics and opticalsystems in order, after a phase of flight followed by a target approachphase, to ensure a high degree of reliability and precision with whichthe munition hits the target.

For example, certain types of missile or guided rocket are steered usinga laser beam. A missile optic detects the laser beam illuminating thetarget and a missile on-board computer determines the flight parametersfor reaching the target.

In general, the guidance optic is situated at the front end of themissile, or of the steered munition more generally, i.e. is situated atthat end of the munition that is directed toward the target, comprises aprotective cap, firstly for protecting the guidance optic from impactswith bodies present in the air during the flight phase, and secondly forpreventing the temperature of the missile steering electronicsassociated with the guidance optic from heating up as a result of theaerodynamic friction against the head (or nose) of the munition.

This cap can thus protect the munition guidance optic, as appropriate,during a firing phase, for example when passing through a diaphragm;during a ballistic phase, in the case of a rocket or of a projectile; orduring a cruising phase, in the case of missiles.

In the state of the art with guided munitions, either the guidance opticis directly exposed to impact with bodies present in the air and toaerodynamic friction or it is protected by a cap that can, onapproaching the target, be detached from the munition body, at the riskof the protective cap detached from the munition body damaging the tailassembly that is deployed at the rear of the rocket or of the missile.

In order to alleviate the disadvantages of steered munitions of theprior art, the invention proposes a steered munition intended to destroya target after at least one flight phase followed by a target approachphase, said munition comprising a munition body of cylindrical shape oflongitudinal axis ZZ′ having, on the same side as a front end Eav of themunition which is the end intended to be directed toward the target, afront body comprising an optic of a guidance device that guides saidmunition toward the target, a cap for protecting the optic, secured tothe munition body, characterized in that the protective cap, in theshape of an ogive of axis of revolution XX′ coincident with thelongitudinal axis ZZ′, being made of a material that can be shatteredinto multiple fragments, comprises at least one recess forming at leastone cavity containing a pyrotechnic device intended to supply propulsiveenergy directly to the walls of the cavity to shatter the protective capinto multiple fragments, in order to free the optic and make themunition guidance device operational during the target approach phase.

Advantageously, the protective cap comprises walls having weakeninggrooves so as to promote regions along which said walls rupture when theprotective cap is being destroyed.

In one embodiment, the steered munition comprises, between theprotective cap and the front body of the munition body, a shield thatprotects the optic of the guidance device.

In an another embodiment, the protective shield comprises a shield bodyof circular cylindrical rounded shape having two main faces and acircular edge of axis coaxial with the longitudinal axis ZZ′, therounded shape of the shield body conforming to the shape of the surfaceof the front body of the munition body.

In another embodiment, the steered munition comprises a clamping bandthat secures the protective cap to the munition body, the clamping bandcomprising, on the same side as the front end Eav of the munition, acircular edge of tapering shape.

In another embodiment, the surface of the front body, of rounded shape,has no discontinuity and no roughness so that it exhibits a continuousaerodynamic profile.

In another embodiment, the front body of the munition body comprises, onthe same side as the front end Eav, a front body part of circularcylindrical shape of diameter D1, of axis of revolution collinear withthe longitudinal axis ZZ′, the front body part comprising a munitionfront body wall of rounded shape including the optic of the guidancedevice, the rounded portion of the munition front body wall beingdirected toward the front end Eav to give the munition a continuousaerodynamic shape when it has been rid of the protective cap.

In another embodiment the protective cap, in the shape of an ogive, ofaxis of revolution XX′, comprises a first recess opening onto a secondrecess of circular cylindrical shape of diameter equal to the diameterD1 of the front body part of the munition body, the first recess of thecap forming, with the rounded-shaped front body wall, centered on thelongitudinal axis ZZ′, a first cavity containing the protective shield.

In another embodiment, the pyrotechnic device comprises a propulsivecharge and an igniter, the igniter comprising electrical contacts foractivating it.

In another embodiment, the first cavity contains the pyrotechnic device.

In another embodiment the protective shield comprises, near its circularedge, a support for supporting the igniter in a plane parallel to thelongitudinal axis ZZ′, the igniter support acting as a spoiler intendedto generate a transverse force when it is subjected to the aerodynamicforces as the cap is being destroyed, and as out-of-balance weight inthe case of a munition that spins on itself.

In another embodiment, the protective cap further comprises, at the sameside as the front end Eav, a third recess of cylindrical shape of axiscollinear with the longitudinal axis ZZ′, and separated from the firstrecess by a dividing wall in a plane perpendicular to the longitudinalaxis ZZ′, the third recess being closed by a nose cone to form a secondcavity containing the pyrotechnic device intended to destroy theprotective cap.

In another embodiment, the protective shield comprises, near itscircular edge, a spoiler intended to generate a transverse force on theshield body when it is subjected to the aerodynamic forces and to causeit to be ejected from the body of the munition, said spoiler also actingas an out-of-balance weight in the case of a munition that spins onitself.

In another embodiment, the protective cap comprises a cap connectionpart extended by a cap end ring having a cap edge of diameter D5 greaterthan the outside diameter D4 of the cap connection part so as to form afirst cap shoulder so that the clamping band can prevent translationalmovement of the cap along the longitudinal axis ZZ′ on the front body ofthe munition body.

In another embodiment, the munition comprises two layers of electricconductors intended to activate the igniter:

-   -   a first layer having one end bonded to one of the main faces of        the shield on the same side as the front body of the munition        body, a central part bonded to the other main face of the shield        on the same side as the first recess of the cap, the other end        of the first layer, in the first cavity being electrically        connected to the electrical contacts for the activation of the        igniter, the first layer passing from one main face of the        shield to the other along a groove on the edge of said shield,    -   a second layer of electric conductors, on the same side as the        munition body, in electrical contact with the end of the first        layer on the same side of the front body of the munition body.

In another embodiment, the front body part is extended toward the rearbody of the munition by an intermediate body of circular cylindricalshape of the same axis of revolution ZZ′ as, and of diameter D2 greaterthan the diameter D1 of, the front body part, so as to form a first bodyshoulder, the intermediate body being extended by the rear body of themunition of diameter D3 greater than the diameter D2 of saidintermediate body, so as to form a second body shoulder.

In another embodiment, the protective cap, secured to the body of themunition by the clamping band, comprises a cap central part of conicalor ogive shape extended, on its larger-diameter side, by a capconnection part that connects the cap to the munition body, of circularcylindrical shape, of outside diameter D4 smaller than the diameter D2of the intermediate body, the cap connection part being extended by acap end ring having a cap edge of diameter D5 greater than the outsidediameter D4 of the cap connection part and less than the diameter D2 ofthe intermediate body so as to form a first cap shoulder intended toprevent translational movement of the cap.

In another embodiment, the cap edge and the first body shoulder eachhave a respective hole for the insertion of a pin that angularly indexesthe cap and the munition body, the internal wall of the first recess ofthe cap comprising a tooth inserted in the groove situated on thecircular edge of the protective shield, the angular indexing pin and thetooth inserted in the groove of the protective shield providingelectrical contact between the two layers and orienting the spoiler ofsaid protective shield at an advantageous clearance angle.

In another embodiment, the cap comprises a series of longitudinalweakening grooves along the walls of the first and second recesses,these grooves being evenly distributed about the axis of revolution XX′of the cap, the cap further comprising a circular weakening groove alongthe periphery of its external surface some distance from the cap edgesuch that said circular weakening groove is located at the tapering endof the clamping band when the cap is mounted on the munition body.

In another embodiment, the cap moreover comprises another circularweakening groove along the periphery of the internal surface of the capformed by the wall of the second recess, some distance from the cap edgesuch that said other weakening groove is located at the end, of diameterD1, of the front body part on the side of the front body wall when thecap is mounted on the munition body, the axis XX′ of the protective capthen coinciding with the longitudinal axis ZZ′ of the munition.

The invention will be better understood with the aid of an example ofhow a guided munition according to the invention is embodied, in theparticular case in which this munition is a rocket, and with referenceto the indexed drawings in which:

FIG. 1 is a partial view in axial section of one example of how a guidedrocket according to the invention is embodied;

FIG. 2 a is a partial view in cross section of a protective cap of therocket of FIG. 1;

FIG. 2 b is a partial perspective view of the cap of FIG. 1;

FIG. 2 c is a view of detail A of the cap showing weakening grooves;

FIG. 3 a is a perspective view of the rocket body of FIG. 1 comprising aprotective shield;

FIG. 3 b shows just the protective shield of the rocket body of FIG. 3a;

FIG. 4 a shows the rocket of FIG. 1 after the cap has been destroyed andbefore the protective shield has been ejected;

FIG. 4 b shows the rocket of FIG. 1 after the cap has been destroyed andafter the shield has been ejected;

FIG. 5 shows an alternative form of embodiment of the rocket of FIG. 1according to the invention;

FIG. 6 is a perspective view of the rocket body of FIG. 5 comprising aprotective shield.

FIG. 1 is a partial view in axial section of one example of how a guidedrocket according to the invention is embodied.

More specifically, FIG. 1 is a partial view in cross section of thefront end Eav of a guided rocket according to the invention. The frontend Eav of the rocket is the end that is directed toward the target whenthe rocket is launched (the head or nose of the rocket) and which,therefore, has an aerodynamic shape for optimal penetration through theair. The other end of the rocket, which has not been depicted in thefigures, is the rear end of the rocket and generally comprises a tailassembly.

The rocket of FIG. 1, of circular cylindrical shape of longitudinal axisZZ′, essentially comprises:

-   -   a rocket body 10 having a front body 14 and a rear body 16        essentially forming the rocket body 10,    -   on the same side as the front body 14 of the rocket, a        protective cap 20 in the form of an ogive of axis of revolution        XX′,    -   a clamping ring 22 that secures the protective cap 20 to the        rocket body 10,    -   between the protective cap 20 and the front body 14, a        protective shield 24 protecting an optic 26 in the front body 14        of the rocket, of a homing head of the rocket, not depicted in        the figures.

The front body 14 of the rocket comprises, on the same side as the frontend Eav, a front body part 28 of circular cylindrical shape of diameterD1, of axis of revolution collinear with the longitudinal axis ZZ′. Thefront body part 28 is extended toward the rear body 16 of the rocket byan intermediate body 30 of circular cylindrical shape with the same axisof revolution ZZ′ and of diameter D2 greater than the diameter D1 of thefront body part 28, so as to form a first body shoulder 32. Theintermediate body 30 is extended by the rear body 16 of the rocket, ofdiameter D3 greater than the diameter D2 of said intermediate body 30,so as to form a second body shoulder 34.

FIG. 2 a is a partial view in cross section of the protective cap 20 ofthe rocket of FIG. 1, FIG. 2 b is a partial perspective view of the capof FIG. 1, and FIG. 2 c is a view of detail A of the cap, showingweakening grooves.

The protective cap 20, secured to the rocket body 10 by the clampingband 22 (see FIG. 1) comprises a cap central part 40 of conical or ogiveshape extended, on its larger-diameter side, by a cap connection part 42that connects the cap to the rocket body 10, of circular cylindricalshape, of outside diameter D4 smaller than the diameter D2 of theintermediate body 30.

The cap connection part 42 is extended by a cap end ring 50 having a capedge 52 of diameter D5 greater than the outside diameter D4 of the capconnection part 42 and less than the diameter D2 of the intermediatebody 30 so as to form a first cap shoulder 54 so that the clamping band22 can prevent translational movement of the cap 20 along thelongitudinal axis ZZ′ on the front body 14 of the rocket.

The protective cap 20 further comprises a first recess 60 opening onto asecond recess 62 of circular cylindrical shape of diameter equal to thediameter D1 of the front body part 28 of the rocket.

The protective cap 20 and the front body part 28 inserted in the secondrecess 62 of diameter D1 are in contact, firstly via their respectivecircular cylindrical surface, these being the internal surface of thecap 20 and the external surface of the front body part 28.

The clamping band 22 (see FIG. 1) coaxial with the longitudinal axis ZZ′has two ends, one end of tapering shape, on the same side as the frontend Eav, and another end on the rocket body side, an external surface 80forming part of the exterior surface of the rocket and internal circularcylindrical surfaces.

The clamping band further comprises:

-   -   on the same side as the end of the body of the rocket, a first        internal clamping surface 82 via which the clamping band 22 is        secured to the circular cylindrical surface of diameter D2 of        the intermediate part 30 of the rocket body 10. The clamping        band 22 is kept in position secured to the rocket body 10 by        known clamping means,    -   on the same side as its tapering end, a second, circular        cylindrical internal surface 90 coaxial with the axis ZZ′ of the        same diameter D4 as the cap connection part 42 and able to slip        over said cap connection part 42.

The internal surface 90 of the clamping band 22 of diameter D4 isconnected by a first band shoulder 94 to a third circular cylindricalinternal surface 96 coaxial with the axis ZZ′, and then, via a secondband shoulder 98, to the first internal clamping surface 82.

The cap 20 is held in its transverse position on the front body part 28of the rocket body 10, in both directions along the axis ZZ′, by theclamping band 22, the first band shoulder 94 butting against the firstcap shoulder 54 and the cap edge 52 butting against the first bodyshoulder 32.

The first recess 60 of the cap 20 forms, with a front body wall 110 ofrounded shape centered on the longitudinal axis ZZ′ of the end of thefront body 14 (see FIG. 1), a first cavity 104 containing the protectiveshield 24. The rounded portion of the front body wall 110 is directedtoward the front end Eav to give the rocket an aerodynamic shape when ithas been rid of the protective cap 20 and of the shield.

The protective cap 20 further comprises, on the same side as the frontend Eav, a third recess 120 (see FIG. 2) of cylindrical shape of axiscollinear with the longitudinal axis XX″ separated from the first recess60 by a dividing wall 124 in a plane perpendicular to the longitudinalaxis XX′. The third recess 120, opening on the same side as the frontend Eav of the rocket, is closed by a nose cone 126 so as to form, withthe third recess 120, a second cavity 128 containing, according to a keyfeature of the guided rocket according to the invention, a pyrotechnicdevice intended to destroy the protective cap 20.

In the embodiment of FIG. 1, the pyrotechnic device essentiallycomprises a propulsive charge 130 and an igniter 132 comprisingelectrical contacts 162 for activating it.

The nose cone 126 is rounded at its end to give the protective cap 20the desired aerodynamic shape.

The cap 20 comprises a series of longitudinal weakening grooves 140along the walls of the first 60 and second 62 recesses (see FIGS. 2 aand 2 b). These longitudinal grooves are evenly distributed about theaxis of revolution XX′ of the cap.

The cap 20 further comprises a circular weakening groove 144 along theperiphery of its external surface some distance from the cap edge 52such that said circular weakening groove 144 is situated at the taperingend of the clamping band 22 when the cap is mounted on the rocket body10. The cap moreover comprises another circular weakening groove 145along the periphery of the internal surface of the cap which is formedby the wall of the second recess 62, some distance from the cap edge 52such that said other weakening groove 145 is situated at the end, ofdiameter D1, of the front body part 28 on the same side as the frontbody wall 110 when the cap 20 is mounted on the rocket body 10. The axisXX′ of the protective cap 20 then coincides with the longitudinal axisZZ′ of the rocket.

The series of longitudinal weakening grooves 140 and the circularweakening grooves 144, 145 along the walls of the cap 20 have thepurpose of making it easier for the cap to disintegrate when thepyrotechnic charge 130 is set off, thus clearing the periphery of theshield 24. This disintegration of the protective cap extends from theother circular weakening groove 145 at the end of the front body part 28of diameter D1, on the same side as the front body wall 110, as far asthe circular weakening groove 144 level with the tapering edge of theclamping band 22.

FIG. 3 a is a perspective view of the rocket body of FIG. 1 comprisingthe protective shield. FIG. 3 b shows just the protective shield of therocket body of FIG. 3 a.

The protective shield 24 comprises a shield body 25 of circularcylindrical rounded shape having two main faces, a rounded circular edge27 and, near the circular edge 27 of the shield, a spoiler 150. Theprotective shield is produced in such a way that its circularcylindrical rounded shape of the shield conforms to the shape of thefront body 14 of the rocket (see FIGS. 1, 3 a and 3 b).

The spoiler 150 of the protective shield 24 is intended to generate atransverse force when it is subjected to aerodynamic forces as the cap20 is being destroyed. This transverse force ensures that the shield 24is ejected sideways and frees the optic 26 of the homing head of therocket.

The shield may be made of metal or of a plastic capable of withstandingthe effects of the pyrotechnic charge.

In the rocket embodiment of FIG. 1, the cap 20 has a hole 158 for theattaching of the igniter 132 in the dividing wall 124 between the first60 and third 120 recesses of the cap, in order to set off the propulsivecharge 130 in the second cavity 128 of the rocket.

The rocket comprises two layers of electric conductors intended toactivate the igniter 132 (see FIG. 1):

-   -   a first layer 160 having one end bonded to one of the main faces        of the shield 24 on the same side as the front rocket body, a        central part bonded to the other main face of the shield 24 on        the same side as the first recess 60 of the cap 20. The other        end of the first layer 160, in the first cavity 104 is        electrically connected to the electrical contacts 162 for the        activation of the igniter 132. The first layer 160 passes from        one main face of the shield 24 to the other along a groove 29 on        the edge of said shield 24.    -   A second layer 170 of electric conductors, on the same side as        the rocket body 10, is in electrical contact with the end of the        first layer 160 on the same side of the front rocket body.

Pressure of contact between the two layers 160, 170 is applied by apresser 172 housed in a recess of the front body 14 of the rocketcomprising a passage 173 for connecting this second layer 170 toactivation electronics, not depicted in the figures, that activate theigniter 132.

The first 160 and second 170 electrical layers are in one and the sameaxial plane passing along the longitudinal axis ZZ′ so that they can bein electrical contact. For this reason, the cap edge 52 and the firstbody shoulder 32 each comprise a respective hole for the insertion of apin 174 which angularly indexes the cap 20 and the rocket body 10.Moreover, the internal wall of the first recess 60 of the cap 20 has atooth 146 inserted in the groove 29 situated on the circular edge 27 ofthe protective shield 24. The angular indexing pin 174 and the tooth 146inserted in the groove 29 of the protective shield provide electricalcontact between the two layers 160, 170 and orient the spoiler 150 ofthe protective shield at an advantageous clearance angle.

In the case of a rocket that spins on itself, the spoiler 150 subjectedto centrifugal force would create an imbalance and strengthen thetransverse component that tends to eject the shield 24.

FIG. 4 a shows the rocket of FIG. 1 after the cap 20 has been destroyedand before the protective shield 24 has been ejected, and FIG. 4 b showsthe situation after the shield has been ejected. After the shield 24 hasbeen ejected, the optic 26 of the homing head is cleared of any obstacleand forms the new rounded aerodynamic profile of the rocket. It shouldbe noted that this new profile, suited to the steered guidance phase, iscontinuous and without roughness.

FIG. 5 shows an alternative form of embodiment of the rocket of FIG. 1according to the invention.

In this alternative form of FIG. 5, the first recess 60 comprise ashield 180 and, in the first cavity 104 formed by the first recess 60and said shield 180, a propulsive charge 183 and an igniter 184 securedto the shield 180. The second cavity 128 is empty.

FIG. 6 is a perspective view of the rocket body of FIG. 5 comprising aprotective shield.

The protective shield 180 comprises a shield body 188 of roundedcylindrical shape conforming to the rounded shape of the front body 14of the rocket and, on the circular edge 189 of the shield 180, a support190 for supporting the igniter 184 in a plane parallel to thelongitudinal axis ZZ′.

The support 190 comprises a fixing hole 192 for the igniter 184 which iselectrically connected to the first 160 and second 170 layers ofelectrical conductors.

In this alternative form the propulsive charge 183 and the igniter 184are near the shield 180.

As in the first embodiment of FIG. 1, the support element 190 supportingthe igniter 184 of the shield 180 acts as a spoiler intended to generatea transverse force when it is subjected to aerodynamic forces when theprotective cap 20 is being destroyed, and as an out-of-balance weight inthe case of a rocket that spins on itself.

The advantage of this alternative form of FIG. 5 is that it simplifiesthe protective cap 20 and ensures that metallic remains of thepyrotechnic device are ejected with the shield on one side of the rockettogether with the fragments of the cap after it has been destroyed.

In another alternative form of embodiment of the rockets of FIGS. 1 and5, the cap 20 comprises only a pyrotechnic charge activated by apyrotechnic cord instead of the layers 160, 170 of electricalconductors. This other alternative form avoids the use of an igniternear the propulsive charge and avoids the expulsion, when the cap isbeing destroyed, of metallic components that could damage the deployedtail assembly of the rocket.

The nose of the rocket, or of the munition in the more general case,contains optical and electronic material which, given a lengthy targetapproach phase and supersonic speed, needs to be protected by theprotective cap. To do this, the material used to create the protectivecap is chosen from materials of the ceramic type or from other sinteredmaterials which have the property of being very weakly, if at all,conductive of the heat energy generated by friction against the air intothe mechanical structure of the rocket. In addition, the mechanicalproperties of ceramic materials make them easy to shatter (they arefriable/brittle), either by deflagration or by detonation depending onthe type of pyrotechnic device chosen.

Through a choice of suitable materials, this invention could be used ina system of the mortar or gun type.

The configuration of the protective shield in the munition according tothe invention makes it possible to protect the optic (for example alens) of the guidance system during flight of the munition up until thepoint that the shield is ejected, and also during storage and logisticsphases and the remainder of the operational (tactical) phase.

This invention also allows a radical change to the aerodynamic profileof the guided munition which in this particular instance changes from anogive shape to a hemispherical shape.

1. A steered munition intended to destroy a target after at least oneflight phase followed by a target approach phase, said munitioncomprising: a munition body of cylindrical shape of longitudinal axisZZ′ having, on the same side as a front end of the munition which is theend intended to be directed toward the target, a front body comprisingan optic of a guidance device that guides said munition toward thetarget, a cap for protecting the optic, secured to the munition body,the protective cap, in the shape of an ogive of axis of revolution XX′coincident with the longitudinal axis ZZ′, being made of a material thatcan be shattered into multiple fragments, comprising at least one recessforming at least one cavity containing a pyrotechnic device intended tosupply propulsive energy directly to the walls of the cavity to shatterthe protective cap into multiple fragments, in order to free the opticand make the munition guidance device operational during the targetapproach phase.
 2. The steered munition as claimed in claim 1, whereinthe protective cap comprises walls having weakening grooves so as topromote regions along which said walls rupture when the protective capis being destroyed.
 3. The steered munition as claimed in claim 1,further comprising, between the protective cap and the front body of themunition body, a shield that protects the optic of the guidance device.4. The steered munition as claimed in claim 3, wherein the protectiveshield comprises a shield body of circular cylindrical rounded shapehaving two main faces and a circular edge of axis coaxial with thelongitudinal axis ZZ′, the rounded shape of the shield body conformingto the shape of the surface of the front body of the munition body. 5.The steered munition as claimed in claim 1, further comprising aclamping band that secures the protective cap to the munition body, theclamping band comprising, on the same side as the front end of themunition, a circular edge of tapering shape.
 6. The steered munition asclaimed in claim 1, wherein the surface of the front body, of roundedshape, has no discontinuity and no roughness so that it exhibits acontinuous aerodynamic profile.
 7. The steered munition as claimed inclaim 1, wherein the front body of the munition body comprises, on thesame side as the front end, a front body part of circular cylindricalshape of diameter D1, of axis of revolution collinear with thelongitudinal axis ZZ′, the front body part comprising a munition frontbody wall of rounded shape including the optic of the guidance device,the rounded portion of the munition front body wall being directedtoward the front end to give the munition a continuous aerodynamic shapewhen it has been rid of the protective cap.
 8. The steered munition asclaimed in claim 7, wherein the protective cap, in the shape of anogive, of axis of revolution XX′, comprises a first recess opening ontoa second recess of circular cylindrical shape of diameter equal to thediameter D1 of the front body part of the munition, the first recess ofthe cap forming, with the rounded-shaped front body wall, centered onthe longitudinal axis ZZ′, a first cavity containing the protectiveshield.
 9. The steered munition as claimed in claim 1, wherein thepyrotechnic device comprises a propulsive charge and an igniter, theigniter comprising electrical contacts for activating it.
 10. Thesteered munition as claimed in claim 9, wherein the first cavitycontains the pyrotechnic device.
 11. The steered munition as claimed inclaim 9, wherein the protective shield comprises, near its circularedge, a support for supporting the igniter in a plane parallel to thelongitudinal axis ZZ′, the igniter support acting as a spoiler intendedto generate a transverse force when it is subjected to the aerodynamicforces as the cap is being destroyed, and as out-of-balance weight inthe case of a munition that spins on itself.
 12. The steered munition asclaimed in claim 8, wherein the protective cap further comprises, on thesame side as the front end, a third recess of cylindrical shape of axiscollinear with the longitudinal axis ZZ′, and separated from the firstrecess by a dividing wall in a plane perpendicular to the longitudinalaxis ZZ′, the third recess being closed by a nose cone to form a secondcavity containing the pyrotechnic device intended to destroy theprotective cap.
 13. The steered munition as claimed in claim 4, whereinthe protective shield comprises, near its circular edge, a spoilerintended to generate a transverse force on the shield body when it issubjected to the aerodynamic forces and to cause it to be ejected fromthe body of the munition, said spoiler also acting as an out-of-balanceweight in the case of a munition that spins on itself.
 14. The steeredmunition as claimed in claim 1, wherein the protective cap comprises acap connection part extended by a cap end ring having a cap edge ofdiameter D5 greater than the outside diameter D4 of the cap connectionpart so as to form a first cap shoulder so that the clamping band canprevent translational movement of the cap along the longitudinal axisZZ′ on the front body of the munition body.
 15. The steered munition asclaimed in claim 9, further comprising two layers of electric conductorsintended to activate the igniter: a first layer having one end bonded toone of the main faces of the shield on the same side as the front bodyof the munition body, a central part bonded to the other main face ofthe shield on the same side as the first recess of the cap, the otherend of the first layer, in the first cavity being electrically connectedto the electrical contacts for the activation of the igniter, the firstlayer passing from one main face of the shield to the other along agroove on the edge of said shield, a second layer of electricconductors, on the same side as the munition body, in electrical contactwith the end of the first layer on the same side of the front body ofthe munition body.
 16. The steered munition as claimed in claim 7,wherein the front body part is extended toward the rear body of themunition by an intermediate body of circular cylindrical shape of thesame axis of revolution ZZ′ as, and of diameter D2 greater than thediameter D1 of, the front body part, so as to form a first bodyshoulder, the intermediate body being extended by the rear body of themunition of diameter D3 greater than the diameter D2 of saidintermediate body, so as to form a second body shoulder.
 17. The steeredmunition as claimed in claim 16, wherein the protective cap, secured tothe body of the munition by the clamping band, comprises a cap centralpart of conical or ogive shape extended, on its larger-diameter side, bya cap connection part that connects the cap to the munition body, ofcircular cylindrical shape, of outside diameter D4 smaller than thediameter D2 of the intermediate body, the cap connection part beingextended by a cap end ring having a cap edge of diameter D5 greater thanthe outside diameter D4 of the cap connection part and less than thediameter D2 of the intermediate body so as to form a first cap shoulderintended to prevent translational movement of the cap.
 18. The steeredmunition as claimed in claim 17, wherein the cap edge and the first bodyshoulder each have a respective hole for the insertion of a pin thatangularly indexes the cap and the munition body, the internal wall ofthe first recess of the cap comprising a tooth inserted in the groovesituated on the circular edge of the protective shield, the angularindexing pin and the tooth inserted in the groove of the protectiveshield providing electrical contact between the two layers and orientingthe spoiler of said protective shield at an advantageous clearanceangle.
 19. The steered munition as claimed in claim 18, wherein the capcomprises a series of longitudinal weakening grooves along the walls ofthe first and second recesses, these grooves being evenly distributedabout the axis of revolution XX′ of the cap, the cap further comprisinga circular weakening groove along the periphery of its external surfacesome distance from the cap edge such that said circular weakening grooveis located at the tapering end of the clamping band when the cap ismounted on the munition body.
 20. The steered munition as claimed inclaim 19, wherein the cap comprises another circular weakening groovealong the periphery of the internal surface of the cap formed by thewall of the second recess, some distance from the cap edge such thatsaid other weakening groove is located at the end, of diameter D1, ofthe front body part on the side of the front body wall when the cap ismounted on the munition body, the axis XX′ of the protective cap thencoinciding with the longitudinal axis ZZ′ of the munition.